5.2 Circular Motion

Question 1

Select all the statements that describe an object accelerating.

A An object that is travelling at a constant speed in the same direction.
B An object that is changing speed and changing direction
C An object that is changing speed but not changing direction
D An object that is not changing speed but is changing direction
E An object at rest

Answer 1

B, C, D

Question 2

At any instant during circular motion, the object’s speed is…

Answer 2

directed tangential to the circular path and the force is perpendicular (at right angles) to the tangential constant speed.

Question 3

What is the name given to the force that keeps an object moving along a circular path?

Answer 3

centripetal force.

Question 4

The path of the object in circular motion is due to the only force acting in the region: the centripetal force.

Select the option that correctly describes the motion of the object if the centripetal force was suddenly removed.

Answer 4

The question tells us that there are no other forces acting in the region. In the absence of any forces, Newton’s 1st Law states that: an object will remain at rest or move at a constant velocity (unless acted upon by a net force). Therefore in this situation where no forces act, the object will (a) continue in a straight line; and (b) not stop. This means that the object will travel in a straight line, as shown below.